Assemble "don't joinedload other side" rule using query._current_path

Discovered during testing for [ticket:3822], the rule added
for [ticket:1495] will fail if the source object has propagated
options set up, which add elements to query._current_path.

Fixes: #3824
Change-Id: I3d96c96fee5f9b247f739d2136d18681ac61f2fe

3 files changed, 18 insertions, 3 deletions

diff --git a/lib/sqlalchemy/ext/baked.py b/lib/sqlalchemy/ext/baked.py
index 3ca94925e..2f658edf3 100644
--- a/lib/sqlalchemy/ext/baked.py
+++ b/lib/sqlalchemy/ext/baked.py
@@ -467,11 +467,15 @@ class BakedLazyLoader(strategies.LazyLoader):
             if rev.direction is interfaces.MANYTOONE and \
                 rev._use_get and \
                     not isinstance(rev.strategy, strategies.LazyLoader):
+
                 q.add_criteria(
                     lambda q:
                     q.options(
-                        strategy_options.Load(
-                            rev.parent).baked_lazyload(rev.key)))
+                        strategy_options.Load.for_existing_path(
+                            q._current_path[rev.parent]
+                        ).baked_lazyload(rev.key)
+                    )
+                )
 
         lazy_clause, params = self._generate_lazy_clause(state, passive)
 
diff --git a/lib/sqlalchemy/orm/strategies.py b/lib/sqlalchemy/orm/strategies.py
index b2cd5b5ec..5f5ab1069 100644
--- a/lib/sqlalchemy/orm/strategies.py
+++ b/lib/sqlalchemy/orm/strategies.py
@@ -615,7 +615,10 @@ class LazyLoader(AbstractRelationshipLoader, util.MemoizedSlots):
                 rev._use_get and \
                     not isinstance(rev.strategy, LazyLoader):
                 q = q.options(
-                    strategy_options.Load(rev.parent).lazyload(rev.key))
+                    strategy_options.Load.for_existing_path(
+                        q._current_path[rev.parent]
+                    ).lazyload(rev.key)
+                )
 
         lazy_clause, params = self._generate_lazy_clause(
             state, passive=passive)
diff --git a/lib/sqlalchemy/orm/strategy_options.py b/lib/sqlalchemy/orm/strategy_options.py
index 2fb13f3cf..0c1ebf404 100644
--- a/lib/sqlalchemy/orm/strategy_options.py
+++ b/lib/sqlalchemy/orm/strategy_options.py
@@ -85,6 +85,14 @@ class Load(Generative, MapperOption):
         self.context = {}
         self.local_opts = {}
 
+    @classmethod
+    def for_existing_path(cls, path):
+        load = cls.__new__(cls)
+        load.path = path
+        load.context = {}
+        load.local_opts = {}
+        return load
+
     def _generate(self):
         cloned = super(Load, self)._generate()
         cloned.local_opts = {}